Graphene oxide wrapped hollow mesoporous carbon spheres as a dynamically bipolar host for lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) hold great potential as a next-generation electrochemical energy storage and conversion system owing to their high theoretical specific capacity (1675 mA h g(-1)). However, the shuttling of polysulfides dissolved in electrolytes with slow redox kinetics has restricted the near-term commercialization of LSBs. Developing a multifunctional host that can tightly bind polysulfides with fast conversion kinetics represents a promise strategy for improving the electrochemical performances of LSBs towards practical applications. Herein, we design three-dimensional graphene oxide wrapped hollow carbon spheres with straight mesoporous channels (termed HMCS@GO) as a novel cathode host for LSBs with several integrated merits: (1) the hollow carbon spheres with a mesoporous shell afford a large interior void for the loading of sulfur species and serve as a conducting substrate for high utilization of the sulfur cathode with reduced polarization; (2) the wrapped graphene oxide layer with rich surface functional groups acts as a polar carrier for effective immobilization of soluble polysulfides and promotes their quick conversion during a charge/discharge process; (3) the hollow carbon spheres also effectively buffer the large volume fluctuation of the sulfur cathode during charge/discharge with enhanced structural integrity during long-term cycling. Experimental data and first-principles density functional theory (DFT) calculations reveal that high electrochemical performance has been realized in LSBs assembled using HMCS@GO as a cathode host. This work can provide new insights into the rational design and fabrication of all carbon-based composite electrodes for useful applications in lithium-sulfur batteries and other electrochemical energy storage and conversion systems.

Automated summary

In this study, a novel cathode host for lithium-sulfur batteries (LSBs) was designed, which consists of three-dimensional graphene oxide wrapped hollow carbon spheres. The new host demonstrated improved electrochemical performance in LSBs through several integrated advantages. Experimental data and calculations showed that high electrochemical performance was achieved in LSBs using this new cathode host.